Thread forming device



June 29, 1954 P. J. WENDEL ET AL THREAD FORMING DEVICE Filed May 9, 1949 Ram OWN TEA N M E .5 w% 1R m E W E C N E R A L C ATTORNEY Patented June 29, 1954 THREAD FORMING DEVICE Peter J. Wendel, Lancaster, and Clarence W.

' Datesman, Jr., Columbia, Pa., assignors to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania Application May 9, 1949, Serial No. 92,124

5 Claims.

This invention relates to a thread forming device and more particularly to an attachment for threading devices suitable for forming threads on cup-shaped metal articles such as closures and the like.

In the threading of metal articles such as closures and the like, one of the devices commonly usedis a rotary threader in which the articles to be threaded are rotated in a closed path past a series of stationary forming dies. A typical rotary threader is disclosed in Merolle Patent No. 2,245,042.

In the device disclosed in the Merolle patent the metal articles to be formed are positioned loosely on a rotating mandrel; and the rotating mandrel revolves about a series of knurling, beading, and threading tools. The mandrel is provided with internal forming tools which cooperate with the stationary knurling, beading, and threading tools to form the article to the shape desired. The articles are placed on the mandrel loosely so that when they are completely formed they may be readily removed therefrom without necessitating unscrewing the same. In order to keep the article in a, true vertical position while it is in engagement with the knurling, beading, and threading dies, a fiat pressure plate is provided which engages the top flat surface of the blank and holds it in a vertical position. This arrangement limits the devices of the Merolle type to the production of fiat-topped closures.

By utilizing the device of our invention it is possible to produce domed closures on rotary threaders of the Merolle type by machining a groove in the pressure plate to fit the contour of the domed closure. This groove which is arcuate in cross section provides only line contact with the top surface of the closures, such line contact being in a line perpendicular to the axis of the rotating carriage carrying the mandrels. This line contact prevents rocking of the closures on the mandrels in a direction perpendicular to the axis of the carriage, but the closure is free to rock in a plane parallel to the axis of the carriage. In order to prevent the rocking of the closures in a plane parallel to the axis of the carriage, we have developed an attachment which surrounds a portion of the mandrel carrying the closure and supports a portion only of the skirt of the closure to prevent the same from rocking in a plane parallel to the axis of the carriage.

In order that our invention may be more readily understood, it Will be described in connection with the attached drawings in. which:

Figure l is a cross-sectional view of the mandrel with a metal closure disposed thereon;

Figure 2 is an elevational view of the closure skirt-supporting attachment;

Figure 3 is an end elevation showing a modification of the skirt-supporting attachment; and

Figure 4 is a cross-sectional view taken on the line IV-IV of Figure 1.

Referring to Figure 1 there is shown a portion of a rotatable carriage 3 carrying a mandrel d rotatable within said carriage. For purposes of describing this invention a portion only of the carriage showing the one mandrel is illustrated; however, it will be understood that the rotatable carriage carries a plurality of mandrels. Adjacent the rotatable carriage 3 is a fixed plate 5 which has attached to its periphery a ring gear 6. The rotatable mandrel 4 is provided with a gear I which is in engagement with the ring gear 6. It will be clear from this disclosure that as the carriage 3 rotates the gear I, which is in engagement with stationary ring gear 6, causes the mandrel 4 to rotate within the carriage 3. Secured to the fixed plate 5 are a beading die 8, a threading die 9, and a knurling die I0. Positioned at the end of mandrel l are the internal cap-forming tools which correspond to the stationary dies 8, S, and Ill. The internal beading tool is designated by the numeral ii, the threading tool by the numeral 12, and the knurling tool by the numeral l3. These tools are all held in place on the mandrel by the screw M. It will be noted that the closure shell I5 positioned on the end of the mandrel 4 has a greater diameter than the internal tools H, I2, and I3. This enables the closure to be easily removed from the mandrel after the beading, threading, and knurling operations have been completed.

Attached to the fixed plate 5 is a pressure plate It which supports the top surface of the closure [5 while the closure is in engagement with the forming dies 8, 9, and I0. Pressure'plate I5 is provided with an arcuate channel designated by the numeral II to conform to the domed surface of the closure. Surrounding a portion of the mandrel 4 is a skirt-supporting element It (Figures 2 and 4). This skirt-supporting element is positioned around a major portion of the rotating mandel 4. Inasmuch as the element It partially covers the gear 1, the element It does not surround the mandrel in the area which is in engagement with the stationary gear 6 on the fixed plate 5.

Inasmuch as the element It does not surround the gear I in the area in which the gears ii and 3 I are in engagement, the portion of the closure shell skirt which is disposed directly above the point at which the gears engage is unsupported, making the skirt easily accessible for engagement by stationary dies 8, 9, and 10. Even though the skirt is not supported in the area in which the stationary dies engage the same, the skirt is supported by the element l8 throughout suflicient of its circumference to prevent rocking of the closure shell. Likewise, in the area disposed 180 from the point at which the gear 'i' engages the stationary gear 5, the lowermost extremity of the closure shell skirt must be exposed to enable removal of the closure shell from the mandrel by means of a skirt-engaging rail which engages the underneath section of the skirt and moves the closure outwardly away from the supporting mandrel. In order to provide an area in which the closure removal means can engage the skirt of the closure to remove the same, the element I8 is cut away as shown at [9 (Figures 1 and 2). The element I8 is secured by means of screws 20 to the movable carriage 3.

Figure 4 shows the element IS in place surrounding the gear 1 and having its flat outer surface in engagement with the bottom edge of the skirt of the closure shell. It will be clear from this view that the dome of the closure shell has only line contact with the channel 6 on the plane parallel with the axis of the mandrel 4, but is kept from rocking by engagement with the element I8.

In Figure 3 there is shown a modification of our invention in which two elements 2| are positioned to surround a portion of the rotating mandrel 4. The elements 2| do not surround the mandrel in the area where the gears B and I are in engagement with one another or the area disposed 180 from the point at which the gears are in engagement. The modification shown in Figure 3 is adapted for the production of large diameter closures.

In the operation of our device the article to be formed is fed through a suitable chute (not shown) onto the rotating mandrel 4. The rotating mandrel 4 carrying the article l5 revolves through a closed path about the axis of the carriage 3. The article which is greater in diameter than the diameter of the mandrel is prevented from rocking by engagement of the top portion of the article with an arcuate groove in the pressure plate and also by engagement of the lowermost portion of the skirt with the element it! which surrounds a portion of the mandrel 4. While the article is so supported, it is rotated past a series of stationary dies 8, 9, and I9 which together with the internal mandrel dies ll, l2, and I3 perform the operation of knurling, threading, and beading of the article. After the article is formed, it is removed from the mandrel and falls into a suitable tote box or other receptacle. The mandrel continues in its circular path, picking up another article; and the cycle is repeated.

It will be clear from the above description that we have provided an attachment for rotary threading machines which will adequately support articles such as closures to prevent the same from tilting on the rotating mandrel while in engagement with the thread forming die. Ihe elements [8 and 2! may be placed on the device when it is built and can be used for all types of metal cap threading, both flat-topped and domed. The only change which is required in converting the machine from the manufacture of one type of closure to the manufacture of the other is to change the pressure plate [8.

While we have illustrated and described certain preferred embodiments of our invention, it will be understood that the same is not so limited, but may be otherwise practiced within the scope of the following claims.

We claim:

1. In an apparatus of the class described, means for forming screw closures, said means comprising a rotatable mandrel, die members carried by said rotatable mandrel for shaping the skirts of closure shells, a rotatable spider carrying said rotatable mandrel, stationary die members disposed in a zone adjacent the path of travel of the rotatable mandrel carried by the spider, the location of the stationary die members being such that they cooperate with the mandrelcarried die members during a portion of the path of travel of the mandrel-carried die members to shape the skirts of closure shells, means carried by said spider for engaging the bottom edge of the skirt of the closure shell while it is on said mandrel to support the skirt of the closure shell while it is being operated upon by the cooperating die members, and means for holding the skirt of said shell in engagement with said supporting means while being operated upon by the cooperating die members.

2. In an apparatus of the class described,

means for forming screw closures, said means comprising a rotatable mandrel, die members carried by said rotatable mandrel for shaping the skirts of closure shells, a rotatable spider carrying said rotatable mandrel, stationary die members disposed in a zone adjacent the path of travel of the rotatable mandrel carried by the spider, the location of the stationary die members being such that they cooperate with the mandrelcarried die members during a portion of the path of travel of the mandrel-carried die members to shape the skirts of closure shells, means carried by said spider for engaging the bottom edge of the skirt of the closure shell while it is on said mandrel to support a portion only of the skirt of the closure shell while it is being acted upon by the cooperating die members, and means for holding the skirt of said shell in engagement with said supporting means while being operated upon by the cooperating die members.

' 3. In an apparatus of the class described, means for forming screw closures, said means comprising a rotatable mandrel, die members carried by said rotatable mandrel for shaping the skirts of closure shells, a rotatable spider carrying said rotatable mandrel, stationary die members disposed in a zone adjacent the path of travel of the rotatable mandrel carried by the spider, the location of the stationary die members being such that they cooperate with the mandrelcarried die members during a portion of the path of travel of the mandrel-carried die members to shape the skirts of closure shells, a plurality of skirt-supporting means carried by the spider and disposed around the mandrel to engage the bottom edge of the skirt of the closure shell while it is on said mandrel to support the skirt of the closure shell while it is being acted on by the cooperating die members, and means for holding the skirt of said shell in engagement with said supporting means while being operated upon by the cooperating die members.

4. In an apparatus of the class described, means for forming screw closures, said means comprising a rotatable mandrel, die members carried by said rotatable mandrel for shaping the skirts of closure shells, a rotatable spider carrying said rotatable mandrel, stationary die members disposed in a zone adjacent the path of travel of the rotatable mandrel carried by the spider, the location of the stationary die members being such that they cooperate with the mandrel-carried die members during a portion of the path of travel of the mandrel-carried die members to shape the skirts of closure shells, a support carried by said spider and surrounding a portion of the mandrel for supporting the skirt of the closure shell to prevent the same from rocking in a lateral direction while it is being acted on by the cooperating die members, and means for holding the skirt of said shell in engagement with said supporting means while being operated upon by the cooperating die members.

5. In an apparatus of the class described, means for forming screw closures, said means comprising a rotatable mandrel, die members carried by said rotatable mandrel for shaping the skirts of closure shells, a rotatable spider carrying said rotatable mandrel, stationary die members disposed in a zone adjacent the path of travel of the rotatable mandrel carried by the spider, the location of the stationary die members being such that they cooperate with the mandrel-carried die members during a portion of the path of travel of the mandrel-carried die members to shape the skirts of closure shells, means carried by said spider for engaging the bottom edge of the skirt of the closure shell While it is on said mandrel to support a portion only of the bottom edge of the skirt of the closure shells, leaving the skirt unsupported at the point at which it is in engagement with the cooperating die members, and means for holding the skirt of said shell in engagement with said supporting means while being operated upon by the cooperating die members.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,900,880 Kramer Mar. '7, 1933 2,308,276 Gibbs Jan. 12, 1943 2,488,015 Ingram Nov. 15, 1949 

